DR. LINDSAY ON WEST-GREENLAND LICHENS. 329 
species, as I regard what is apparently its distinctive character (the clothing with sphæ- 
rophoroid isidia) as a mere condition common to, or in, various Parmelie and other folia- 
ceous lichens in Arctic or northern countries. Similar states of omphalodes occur in 
the present collection, mostly in microphylline forms, the isidia compound or ramulose, 
aggregated sometimes in spherical detachable masses, as in the type. The same sphæro- 
phoroid conditions of P. saxatilis and other species occur in the present collection from 
the Vancouver-Island area of N. W. America. 
Greenland varieties of saxatilis occasionally exhibit other forms of abnormal growths 
on the thallus, e. y. granulations, warts, squamules, or minute secondary laciniæ. All 
forms of the plant, including those which are most spheerophoroid, and all parts of the 
thallus, including the smooth peripheral laciniæ, as well as all colours of the thallus, 
including the whitish leucochroa forms, exhibit the same reactions, or their absence, 
with chemical tests, the reaction-colour being most vivid (where developed at all) 
in forms with the palest thallus. Bleaching-solution gives no reaction. Potash gives 
a lemon-yellow, generally very vivid and beautiful— developed at once—sometimes 
quickly passing into a rich orange-red. Omphalodes, and the passage-forms into the 
type, give the same reaction with potash as saxatilis, that is, a vivid green or lemon- 
yellow. Lemon-yellow however, is, sometimes equally produced by the application of 
water; and in no case has the reaction any significance or value. 
The thallus of sazatilis has, in the natural state, sometimes as distinctly a saffron 
colour as Solorina crocea. Its surface is occasionally smooth, free from the usual 
retieulations or fossulations, approaching perlata. In the same forms, which are usually 
macrophylline, the colour is frequently glaucous or bluish. These characteristics of 
colour and smoothness are always more visible on the peripheral laciniz, which are 
simpler in all respects than those which are more central. 
There are various passage-forms between the type and omphalodes, the only differ- 
ence being one affecting colour. The normal thallus of saxatilis is sometimes peripher- 
ally olive. Microphylline forms of omphalodes sometimes bear, to a slighter extent, the 
same subspherical, but more minute, sphærophoroid growths that occur in the type— 
the isidia being very narrow or slender, branching considerably, closely aggregated, 
sometimes constituting (when isolated) small balls. Some forms (mostly microphylline) 
of omphalodes closely resemble certain conditions of P. olivacea, P. fahlunensis, and P. 
arctica. It passes into panniformis, which is sometimes jet-black and glossy. Some- 
times a single specimen exhibits the characters, in different parts, of saxatilis, omphalodes, 
and panniformis, with a normally smooth, or an isidioid, thallus. Another abnormal or 
unusual condition of sazatilis (about Jakobshavn) resembles the vittata var. of P. 
physodes. 
All the Greenland forms of sazatilis examined by me were sterile as to apot 
but in some cases the peripheral lacinie were copiously black-punctate with spermo- 
gonia*. The thallus, moreover, was frequently the site of various parasitic growths. 
> i ia of P. saxatilis and their contents are figured and described in my * Monograph of 
Prud en 3, 4; and ‘Mem. Spermog.’ p. 226, and pl. xii. figs. 17-19. They may ee 
trasted with the pycnidia on var. sulcata, Tayl., from Connemara (Moore), which contain stylospores "00016" long 
and :00012” broad (Mem. Spermog. p. 228, and pl. xii, figs. 20, 21). $e 
VOL. XXVII. 
hecia ; 
